Scroll compressors have widely been used as compressors connected to a refrigerant circuit for performing a refrigeration cycle to compress a refrigerant. The scroll compressor includes a fixed scroll and an orbiting scroll, each of which has an end plate and a spiral lap protruding from a front surface of the end plate. The laps of the fixed scroll and the orbiting scroll mesh with each other to form a compression chamber. When the orbiting scroll revolves, a low temperature and low pressure refrigerant is sucked into the compression chamber through an outer end of the lap, and a high temperature and high pressure refrigerant compressed in the compression chamber is discharged through an inner end of the lap.
Patent Document 1 discloses a scroll compressor in which an intermediate pressure gaseous refrigerant is introduced to a compression chamber in the course of compression. In the scroll compressor disclosed by the Japanese Patent Publication No. 2007-178052, refrigeration oil separated from a refrigerant discharged from the scroll compressor is supplied to the compression chamber in the course of compression together with the intermediate pressure gaseous refrigerant.
According to a scroll compressor disclosed by 2 Japanese Patent Publication No. 2005-009332, a clearance between an end face of the lap and a front surface of the end plate facing each other is gradually increased in a direction from an outer end of the lap to an inner end of the lap. In this scroll compressor, the clearance between the lap and the end plate is increased with decreasing distance from the inner end of the lap where temperature is high and significant thermal expansion occurs, so that the clearance between the lap and the end plate is not reduced too much when the scroll compressor is operated.